Abstract: A device for generating short-wavelength electromagnetic radiation based on a gas discharge plasma calls for suppressing droplet formation of liquid coating material that is applied to disk electrodes rotated at high rotational frequencies and ensuring a uniform layer thickness. The device has two rotating disk electrodes, each having two lateral surfaces and a circumferential surface, provided with a reservoir with liquid coating material and a wiper for removing excess coating material. The wiper, which has a U-shaped form comprising two legs parallel to the lateral surfaces of the disk electrode and a crosspiece transversely over the circumferential surface, is at least axially movably supported and has impingement elements at the legs so that it is automatically axially adjustable by means of the coating material which is transported on the lateral surfaces and pressed into the gap during the rotation of the disk electrode.

Abstract: A method for producing electromagnetic radiation comprising: firing a first laser pulse and generating a plasma region, the first laser pulse penetrating at least partially into the plasma region to create a plasma density wake in the plasma region; providing a group of charged particles in the plasma region arranged so as to be accelerated in the plasma density wake of the first laser pulse; reflecting the first laser pulse after the first laser pulse has penetrated into the plasma region, to give a reflected laser pulse; and arranging the reflected laser pulse to interact with the group of charged particles to generate an electromagnetic radiation.

Abstract: A system for separating plasma pumping light and collected broadband light includes a pump source configured to generate pumping illumination including at least a first wavelength, a gas containment element for containing a volume of gas, a collector configured to focus the pumping illumination from the pumping source into the volume of gas to generate a plasma within the volume of gas, wherein the plasma emits broadband radiation including at least a second wavelength and an illumination separation prism element positioned between a reflective surface of the collector and the pump source and arranged to spatially separate the pumping illumination including the first wavelength and the emitted broadband radiation including at least a second wavelength emitted from the plasma.

Abstract: A method for sustaining a plasma includes providing a volume of a gas; generating illumination of a first selected wavelength; and forming a first plasma species in a first region of the gas and a second plasma species in a second region of the gas by focusing the illumination of the first wavelength into the volume of gas, the first region having a first average temperature and a first size, the second region having a second average temperature and a second size, the illumination of the first selected wavelength transmitted by the second plasma species, the illumination of the first selected wavelength absorbed by the first plasma species by tuning the first selected wavelength of the illumination to an absorption line of the first plasma species, the absorption line being associated with an ionic absorption transition or an excited neutral transition of the first plasma species.

Abstract: A cell for a vacuum ultraviolet plasma light source, the cell having a closed sapphire tube containing at least one noble gas. Such a cell does not have a metal housing, metal-to-metal seals, or any other metal flanges or components, except for the electrodes (in some embodiments). In this manner, the cell is kept to a relatively small size, and exhibits a more uniform heating of the gas and cell than can be readily achieved with a hybridized metal/window cell design. These designs generally result in higher plasma temperatures (a brighter light source), shorter wavelength output, and lower optical noise due to fewer gas convection currents created between the hotter plasma regions and surrounding colder gases. These cells provide a greater amount of output with wavelengths in the vacuum ultraviolet range than do quartz or fused silica cells. These cells also produce continuous spectral emission well into the infrared range, making them a broadband light source.

Abstract: A laser device includes a seed laser, an amplifier, a detector, and an optical element arranged to direct radiation emitted by the seed laser towards a plasma generation site. The optical element is arranged to direct towards the detector amplified spontaneous emission radiation which has been emitted by the seed laser and has been reflected from a droplet of fuel material. The detector is arranged to trigger generation of a laser radiation pulse by the seed laser when the reflected amplified spontaneous emission radiation is detected.

Abstract: An apparatus and method is disclosed which includes or employs an EUV light source comprising a laser device outputting a laser beam, a beam delivery system directing the laser beam to an irradiation site, and a material for interaction with the laser beam at the irradiation site to create an EUV light emitting plasma for use in processing substrates.

Abstract: The invention provides microchannel lasers having a microplasma gain medium. Lasers of the invention can be formed in semiconductor materials, and can also be formed in polymer materials. In a microlaser of the invention, high density plasmas are produced in microchannels. The microplasma acts as a gain medium with the electrodes sustaining the plasma in the microchannel. Reflectors are used with the microchannel for obtaining optical feedback to obtain lasing in the microplasma gain medium in devices of the invention for a wide range of atomic and molecular species. Several atomic and molecular gain media will produce sufficiently high gain coefficients that reflectors (mirrors) are not necessary. Microlasers of the invention are based on microplasma generation in channels of various geometries. Preferred embodiment microlaser designs can be fabricated in semiconductor materials, such as Si wafers, by standard photolithographic techniques, or in polymers by replica molding.

Abstract: A laser device includes an optical resonator, a microwave driven discharge device, and a source for a second gas. The microwave driven discharge device is disposed relative to the optical resonator. The microwave driven discharge device operates at a discharge power and gas flow rate to produce a selected amount of energetic singlet oxygen metastables flowing in the direction of the optical resonator. The second source for the second gas is disposed between the optical resonator and the microwave driven discharge device. The second gas reacts with the selected amount of energetic singlet oxygen metastables to form an excited species in an amount sufficient to support lasing of the excited species in the optical resonator.

Abstract: A saturable absorber (SA) is constructed using a fiber taper embedded in a carbon nanotube/polymer composite. A fiber taper is made by heating and pulling a small part of standard optical fiber. At the taper's waist light is guided by the glass-air interface, with an evanescent field protruding out of the taper. Carbon nanotubes mixed with an appropriate polymer host material are then wrapped around the fiber taper to interact with the evanescent field. Saturable absorption is possible due to the unique optical properties of the carbon nanotubes. The device can be used in mode-locked lasers where it initiates and stabilizes the pulses circulating around the laser cavity. The SA can be used in various laser cavities, and can enable different pulse evolutions such as solitons, self-similar pulses and dissipative solitons. Other applications include but are not limited to optical switching, pulse cleanup and pulse compression.

Abstract: A radiation system includes a target material supply configured to supply droplets of target material along a trajectory, and a laser system that includes an amplifier and optics. The optics are configured to establish a first beam path which passes through the amplifier and through a first location on the trajectory, and to establish a second beam path which passes through the amplifier and through a second location on the trajectory. The laser system is configured to generate a first pulse of laser radiation when photons emitted from the amplifier are reflected along the first beam path by a droplet of target material at the first location on the trajectory. The laser system is configured to generate a second pulse of laser radiation when photons emitted from the amplifier are reflected along the second beam path by the droplet of target material at the second location on the trajectory.

Abstract: A liquid supply device includes a liquid cartridge, which has a liquid chamber that stores liquid, a cartridge mounting portion, and a surface detector. The liquid chamber has a first portion, a second portion, and a third portion. The liquid cartridge removably attaches to the cartridge mounting portion. The surface detector detects a surface of the liquid stored in the liquid chamber. A horizontal cross-sectional area of the first portion of the liquid chamber is less than each of a horizontal cross-sectional area of the second portion and the third portion of the liquid chamber, and the first portion of the liquid chamber is positioned between the second portion and the third portion of the liquid chamber in a direction orthogonal to the horizontal cross-sectional area of the first portion of the liquid chamber.

Abstract: A laser-sustained plasma light source with a bulb for enclosing a relatively cool gas environment, and an electrode disposed at least partially within the gas environment. A power supply applies a potential to the electrode, where the power supply is sufficient to create a corona discharge at the electrode within the gas environment, and the power supply is not sufficient to produce an arc discharge within the gas environment. The corona discharge thereby produces a relatively heated gas environment. A pump laser source focuses a laser beam within the gas environment, where the laser beam is sufficient to ignite a plasma in the relatively heated gas environment, but is not sufficient to ignite a plasma in the relatively cool gas environment.

Abstract: The present invention relates to a method and device for generating optical radiation, in particular EUV radiation or soft x-rays, by means of an electrically operated discharge. A plasma (15) is ignited in a gaseous medium between at least two electrodes (1, 2), wherein said gaseous medium is produced at least partly from a liquid material (6) which is applied to one or several surface(s) moving in the discharge space and is at least partially evaporated by one or several pulsed energy beams. In the proposed method and device at least two consecutive pulses (9, 18) are applied within a time interval of each electrical discharge onto said surface(s). With this measure, the collectable conversion efficiency is increased compared to the use of only one single energy pulse within each electrical discharge.

Abstract: A laser device includes an optical resonator, a microwave driven discharge device, and a source for a second gas. The microwave driven discharge device is disposed relative to the optical resonator. The microwave driven discharge device operates at a discharge power and gas flow rate to produce a selected amount of energetic singlet oxygen metastables flowing in the direction of the optical resonator. The second source for the second gas is disposed between the optical resonator and the microwave driven discharge device. The second gas reacts with the selected amount of energetic singlet oxygen metastables to form an excited species in an amount sufficient to support lasing of the excited species in the optical resonator.

Abstract: An arrangement for the generation of radiation by a gas discharge has the object of achieving a considerable reduction in the inductance of the discharge circuit for the gas discharge while simultaneously increasing the lifetime of the electrode system. Also, the use of different emitters is ensured. A rotary electrode arrangement accommodated in the discharge chamber contains electrodes which are rigidly connected to one another at a distance from one another and are mounted so as to be rotatable around a common axis. Capacitor elements of a high-voltage power supply for generating high-voltage pulses for the two electrodes are arranged in a free space formed by the mutual distance. The electrodes are electrically connected to the capacitor elements and to a voltage source for charging the capacitor elements.

Abstract: It is made possible to provide an optical waveguide system that has a coupling mechanism capable of selecting a wavelength and has the highest possible conversion efficiency, and that is capable of providing directivity in the light propagation direction. An optical waveguide system includes: a three-dimensional photonic crystalline structure including crystal pillars and having a hollow structure inside thereof; an optical waveguide in which a plurality of metal nanoparticles are dispersed in a dielectric material, the optical waveguide having an end portion inserted between the crystal pillars of the three-dimensional photonic crystalline structure, and containing semiconductor quantum dots that are located adjacent to the metal nanoparticles and emit near-field light when receiving excitation light, the metal nanoparticles exciting surface plasmon when receiving the near-field light; and an excitation light source that emits the excitation light for exciting the semiconductor quantum dots.

Abstract: A radiation source comprises an anode and a cathode that are configured and arranged to create a discharge in a gas or vapor in a space between anode and cathode and to form a plasma pinch so as to generate electromagnetic radiation. The gas or vapor may comprise xenon, indium, lithium and/or tin. The radiation source may comprise a plurality of discharge elements, each of which is only used for short intervals, after which another discharge element is selected. The radiation source may also comprise a triggering device, which device can facilitate improving the exact timing of the pinch formation and thus the pulse of EUV radiation. The radiation source may also be constructed to have a low inductance, and operated in a self-triggering regime.

Abstract: Controlled avalanche driver circuits and apparatuses for gas lasers. One embodiment typically delivers short, rapid, high voltage ionizing pulses in combination with an electric field whose magnitude is too low to sustain a normal glow discharge. The plasma is typically impedance matched with the pulse-forming network. Pre-ionization pulses may be generated. The circuits enable very high power, stable lasers.

Abstract: A method of producing extreme ultraviolet radiation (EUV) or soft X-ray radiation by means of an electrically operated discharge, in particular for EUV lithography or for metrology, in which a plasma (22) is ignited in a gaseous medium between at least two electrodes (14, 16) in a discharge space (12), said plasma emitting said radiation that is to be produced. The gaseous medium is produced from a metal melt (24), which is applied to a surface in said discharge space (12) and at least partially evaporated by an energy beam, in particular by a laser beam (20).

Abstract: The invention concerns a radiation source, comprising an anode (2), a cathode (3), an electric discharge gap (4) between the anode (2) and the cathode (3) and a gas input conduit (30) in the discharge gap (4). The gas input conduit (30) is electrically connected to the anode and the cathode. The invention is characterized in that the gas input conduit (30) is supplied with gas by a gas supply conduit (32), designed to form between its portion (42) connected to the gas input conduit (30) and another of its portions connected to a fixed potential, an electric impedance such that it counters the generation of electric discharges inside the gas input conduit (30).

Abstract: Saturated tabletop lasers having increased output energy and operating at 5 Hz repetition rate, were demonstrated at wavelengths about 18.9 nm for molybdenum targets, 16.4 nm for ruthenium targets, 14.7 nm for palladium targets, 13.9 nm for silver targets, and 13.2 nm for cadmium targets in transitions of nickel-like ions. The results were obtained using a sequence of two, plasma-generating pre-pulses, each having sub-Joule energy followed after a selected delay period by picosecond laser plasma excitation pulses having with an energy of about 1 J at angles of incidence optimized for maximum energy deposition.

Abstract: The object of the invention in an arrangement for generating extreme ultraviolet radiation by an electrically operated gas discharge is to achieve an improvement in the adjustment of the layer thickness when applying a molten metal to the electrode surfaces and to provide better protection against the uncontrolled spreading of molten metal into the environment that is associated with an increase in the rotational speed of the electrodes. In particular, it should be possible to increase the rotational speed to the extent that unconsumed discharge zones of the electrodes are always situated in the discharge area at repetition frequencies of several kilohertz. An edge area to be covered has at least one receiving area which extends circumferentially in a closed manner along the edge of the electrode on the electrode surface and which is constructed so as to be wetting for the molten metal and to which a liquid dispensing nozzle is directed for regenerative application of the molten metal.

Abstract: Controlled avalanche driver circuits and apparatuses for gas lasers. One embodiment typically delivers short, rapid, high voltage ionizing pulses in combination with an electric field whose magnitude is too low to sustain a normal glow discharge. The plasma is typically impedance matched with the pulse-forming network. Pre-ionization pulses may be generated. The circuits enable very high power, stable lasers.

Abstract: The present invention provides a polarization dependency-free, gain-saturated high function semiconductor optical amplifier and optical module at industrially low cost. The gist of the present invention is to structurally separate the optical signal propagating waveguide from another optical waveguide which serves as a lasing optical cavity for optical amplification in such a manner that the two optical waveguides are formed in the same plane but not parallel to each other.

Abstract: The invention is directed to an arrangement for generating pulsed currents for gas discharge pumped radiation sources, particularly with high repetition rates and high current strengths for generating plasma emitting EUV radiation.

Abstract: An extreme ultraviolet radiation generator is disclosed in which Xenon gas is continuously ejected from a high pressure nozzle into a low pressure chamber to generate Xenon atom clusters which are irradiated with a high repetition rate pulsed laser to form a plasma and yield quasi-continuous EUV generation. The nozzle has a beveled outer rim to enable the focus point of the laser light to be brought close to the nozzle. The nozzle is cooled to a temperature at which background Xenon gas condenses onto the nozzle forming a protective layer. A gas compressor serves to recirculate the Xenon gas and batch purification triggered by a mass spectrometer monitoring gas purity may be periodically applied.

Abstract: A main laser beam is focused to irradiate a tip of a high-density spouting gas flow formed by heating and then vaporizing a target material by a light beam for preheating making it to the plasma. As the result, the generation of a fast debris in the target material can be suppressed. And a discharge of the fast debris from the target material is also suppressed and extinguished by heating and then vaporizing them by a light beam for transpiration which is emitted at an adjusted time after the generation of the plasma. Thus, the fast debris which still appears in the plasma formed after preheating can be almost perfectly vaporized and extinguished by the light beam for transpiration.

Abstract: In laser-plasma generation, a fluid of target material is jet out to form a jet tube target 21 having a diameter ? and a wall thickness ? with a shell and a hollow space within the shell by using a core-column. A plurality of pulse-like laser beams 30 are directed to the jet tube target radially and equiangularly-spaced directions and are simultaneously focused and irradiated onto the jet tube target to generate the plasma.

Abstract: Methods and apparatus are provided for cleaning and passivating laser discharge chambers with plasmas. In one embodiment, an oxygen based plasma is formed in a plasma source external to the laser discharge chamber by applying a radiofrequency signal to oxygen containing gases. The oxygen based plasma is drawn into the laser discharge chamber, where it reacts with contaminants and cleans internal surfaces. After cleaning, a fluorine based plasma is formed in the plasma source and drawn into the laser discharge chamber to passivate internal surfaces. In another embodiment, cleaning with the oxygen based plasma is not used since some level of cleaning is accomplished with the fluorine based plasma. In another embodiment, oxygen based plasmas and fluorine based plasmas are formed in the laser discharge chamber by applying a radiofrequency signal to a laser discharge chamber electrode.

Abstract: Collector optics (70) for an EUV radiation source (10) for collecting EUV radiation (78). The collector optics (70) includes an elliptical dish reflector (72) where light generated at a focal point (76) of the reflector (72) is collected by the reflector (72) and is directed to a collection location (82). A frustal annular reflector (90) is positioned around an outer edge (84) of the dish reflector (72) to collect more of the EUV radiation (78) that may otherwise be lost. The radiation (78) reflected by the annular reflector (90) is directed to a center axicon reflector (94) positioned between the focal point (76) of the dish reflector (72) and the collection location (82) to redirect the radiation (78) reflected by the annular reflector (90) to be within a predetermined collection angle.

Abstract: Injection efficiency is greatly improved by chemically bonding an organic light emission molecule to an electrode, so as to realize a high efficiency light emission type of flat panel display and a high efficiency laser device, and realize a light emission type of flat panel display and a laser device which have higher performance than conventional organic light emission molecular devices.

Abstract: It has been demonstrated that debris generation within an electric capillary discharge source, for generating extreme ultraviolet and soft x-ray, is dependent on the magnitude and profile of the electric field that is established along the surfaces of the electrodes. An electrode shape that results in uniform electric field strength along its surface has been developed to minimize sputtering and debris generation.

Abstract: The present invention relates to a method for processing an optical signal is provided. An optical signal is input into an optical waveguide structure for providing a nonlinear effect. As a result, the optical signal undergoes chirping induced by the nonlinear effect. An output optical signal output from the optical waveguide structure is supplied to an optical bandpass filter to thereby extract components except a small-chirp component from the output optical signal. The optical bandpass filter has a pass band including a wavelength different from the wavelength of the optical signal. By extracting the components except the small-chirp component from the output optical signal in the form of pulse, it is possible to remove intensity fluctuations or accumulated noise especially at a top portion and/or a low-power portion of the pulse.

Abstract: An extreme ultraviolet and soft x-ray radiation electric capillary discharge source that includes a boron nitride housing defining a capillary bore that is positioned between two electrodes one of which is connected to a source of electric potential can generate a high EUV and soft x-ray radiation flux from the capillary bore outlet with minimal debris. The electrode that is positioned adjacent the capillary bore outlet is typically grounded. Pyrolytic boron nitride, highly oriented pyrolytic boron nitride, and cubic boron nitride are particularly suited. The boron nitride capillary bore can be configured as an insert that is encased in an exterior housing that is constructed of a thermally conductive material. Positioning the ground electrode sufficiently close to the capillary bore outlet also reduces bore erosion.

Abstract: A new laser oscillation device is provided which is capable of readily cooling down a laser medium without employing any large-size complicated separate or discrete devices such as fan blowers while at the same time improving the laser oscillation efficiency to thereby easily generate high-output laser light. To this end, a Lorentz force drive electromagnetic pump means and a cooling means are provided in a way such that the Lorentz force drive electromagnetic pump means is operable to drive the laser medium while allowing the cooling means to cool down the laser medium being driven.

Abstract: A new laser oscillation device is provided which is capable of readily cooling down a laser medium without employing any large-size complicated separate or discrete devices such as fan blowers while at the same time improving the laser oscillation efficiency to thereby easily generate high-output laser light. To this end, a Lorentz force drive electromagnetic pump and a cooling device are provided in a way such that the Lorentz force drive electromagnetic pump is operable to drive the laser medium while allowing the cooling device to cool down the laser medium being driven.

Abstract: An extremely compact soft x-ray and/or extreme ultraviolet laser is disclosed that can be repetitively fired within short time intervals. The laser generates a plasma within a capillary (3) by flowing through the capillary (3) a fast high current pulse generated by a very compact liquid dielectric (1) transmission line (9) geometry.

Abstract: Two techniques for producing plasma x-ray laser amplifiers, encompassing laser generated high density, micron-sized plasma columns, and microwave driven low density, large plasma volumes which provide the population inversions necessary for x-ray lasing to occur in the plasmas. The laser driven plasma is created by short-pulse, high power laser beams produced by chirped pulse amplification techniques, which are confined to micron-sized cylindrical channels by self-focusing effects and electron density conditioning means. The extremely high powers provide for complete stripping of medium to high Z atoms, which allows for recombination cascading to produce population inversions on the higher energy x-ray transition levels. The very short plasma creation times allow a laser produced "seed" x-ray pulse to be properly timed for injection into the plasma when population inversions reach maximum levels.

Abstract: A gas laser includes a plurality of electrically conductive electrodes contained within a hollow housing that contains a laser gas medium. The electrodes surround and define a laser bore in which a plasma is excited by the electrodes. Each of the electrodes defining the laser bore has an ungrounded electrical potential that provides improved laser gain at a lower gas temperature. Each of the electrodes may be driven with a controlled, varying electrical potential, such as a radio frequency electrical potential.

Abstract: An X-ray laser generating apparatus comprises a laser oscillator for generating a pulse laser beam, a pulse train converter for converting the pulse laser beam into a pulse train laser beam, an optical device for focusing the pulse train laser beam to a thin line, a target material placed at the laser beam focused position and generating high temperature plasma containing highly charged ions with irradiation of the linearly focused pulse train laser beam, a vacuum chamber for keeping a vicinity of the irradiated region of the target material under a decompressed state, and a pair of X-ray reflecting mirrors positioned on both sides of the target material and on the extended thin line, and at least one of the paired mirrors partially transmits X-ray.

Abstract: The improved metal vapor laser capable of cold operation performs plasma etching on a vaporizing metal within a laser tube in the presence of a reactive gas so that the metal is vaporized at temperatures below its boiling point to effect laser oscillation. The laser can be operated at much lower temperatures than a conventional hot-operating version which produces metal vapors by thermal evaporation; in addition, the laser will experience a smaller heat loss while undergoing limited thermal damage to its structural members; further, laser light can be oscillated to produce high output power and, at the same time, the warmup time can be shortened significantly.

Abstract: A gas laser, in particular a CO.sub.2 laser, contains as laser medium a gas that is excited into a plasma by a HF energy supply, in particular a microwave energy supply, whereas the HF waves are coupled into the laser medium (4) through a rectangular waveguide (1). In order to obtain a compact structure with an efficient coupling of the HF energy, coupling is ensured by means of a ribbon-shaped waveguide (3) that projects into the rectangular waveguide (1) and thus also allows the outcoupling on all sides of the rectangular waveguide.

Abstract: Optical guiding of intense laser pulses over a distance of more than one Rayleigh length in a plasma is discussed herein using a multi-pulse technique. The first pulse or pulse sequence prepares a shock-driven, axially-extended radial electron density profile which guides a second pulse or sequence of pulses. The profile is also capable of guiding x-rays. The channel will support mode structure exactly analogous to that of an optical fiber waveguide. The method provides a means for guiding of a high intensity optical laser pulse or x-rays over distances well in excess of a Rayleigh length. The distances over which guiding occurs is limited only by the length of the preformed plasma and absorption and possible backscattering of the guided EM radiation. Applications of the method allow for compact x-ray laser devices and electron particle accelerators.

Abstract: A device for generating and guiding an electric discharge current including a first electrode, second electrode and a material arranged between the first and second electrode. The device uses a laser for generating photons having energies equal to the energy between two excited electronic states of the material. The photons fill a region of the material from the first electrode through the material to the second electrode ionizing the region of the material between the first and second electrodes. A voltage generating unit connected to the first and second electrodes applies a voltage between the first and second electrodes thereby generating the electric discharge which follows an ionized path in the region between the first and second electrodes.

Abstract: A device and method for generating and guiding an electric discharge current including a first electrode, a second electrode and a material arranged between the first and second electrodes. The device and method involve the use of a laser for generating photons having energies equal to the energy between two excited electronic states of the material. The photons fill a region of the material from the first electrode through the material to the second electrode, ionizing the region of the material between the first and second electrodes. A voltage generating unit connected to the first and second electrodes applies a voltage between the first and second electrodes thereby generating the electric discharge which follows an ionized path in the region between the first and second electrodes. A solenoid is arranged around the housing so that the magnetic field which it produces is oriented approximately along the ionized path, thereby providing improved confinement of the electric discharge.

Abstract: A stripline laser wherein the distance between a mirror and a stripline is minimized without modifying the characteristics of the laser is provided. The stripline laser prevents damaging of the mirror due to plasma discharge by providing at least two insulating strips arranged between oppositely polarized electrodes. Electrically conductive paths lie between the insulating strips. The insulating strips are arranged to guarantee a voltage division. The voltage division maintains the voltage of the electrically conductive path neighboring the mirror below a plasma-maintaining voltage.

Abstract: Apparatus and method of providing for the excitation of a pulsed laser in which the pulsed excitation energy is provided to the laser plasma volume in a series of bursts, each burst being characterized by containing sufficient pulses to sustain the laser pumping current and by being separated from the previous bursts by sufficient time for the laser plasma to recombine. Application of the burst mode enhancement technique is described with reference to a PIE or photo-initiated, inpulse-enhanced, electrically excited plasma excitation process.

Abstract: An X-ray laser (10) that lases between the K edges of carbon and oxygen, i.e. between 44 and 23 Angstroms, is provided. The laser comprises a silicon (12) and dysprosium (14) foil combination (16) that is driven by two beams (18, 20) of intense line focused (22, 24) optical laser radiation. Ground state nickel-like dysprosium ions (34) are resonantly photo-pumped to their upper X-ray laser state by line emission from hydrogen-like silicon ions (32). The novel X-ray laser should prove especially useful for the microscopy of biological specimens.

Abstract: An x-ray laser comprising a first hydrogenic ion having a nuclear charge Z lasing on a 3-2 Balmer-.alpha. transition, a second hydrogenic ion having a nuclear charge Z/2 emitting Lyman-.alpha. and Lyman-.beta. photons, wherein n=2 electrons of the first hydrogenic ion are excited to the n=4 and n=6 level by resonance absorption of Lyman-.alpha. and Lyman-.beta. photons from the second hydrogenic ion. The invention results in an increase in population inversion and gain to saturation, an improvement in overall efficiency and an increase in plasma size.